The History of the Church is a vital part of the Orthodox Christian faith. Orthodox Christians are defined significantly by their continuity with all those who have gone before, those who first received and preached the truth of Jesus Christ to the world, those who helped to formulate the expression and worship of our faith, and those who continue to move forward in the unchanging yet ever-dynamic Holy Tradition of the Orthodox Church.

870 Gradual collapse of the Moravian mission beginning with the death of Prince Rostislav of Moravia, who is captured and deposed by his nephew, Svátopulk, who favours more the Latin liturgy and Bavarian clergy represented by the Frankish Bp. Wiching of Nitra (consecrated in 880 as the first Bp. of Nitria);[note 1] Conversion of Serbia; Arabs conquer Malta from the Byzantines; martyrdom of Edmund, King of East Anglia.

877 Arab Muslims conquer all of Sicily from Byzantium and make Palermo their capital.

878 King Alfred the Great of Wessex defeats Vikings; the Treaty of Wedmore divides England between the Anglo-Saxons and the Danes (the Danelaw).

879-880 Eighth Ecumenical Council held in Constantinople attended by 383 fathers passing 3 canons, confirms Photius as Patriarch of Constantinople, anathematizes additions to the Nicene-Constantinopolitan Creed, and declares that the prerogatives and jurisdiction of the Roman pope and the Constantinopolitan patriarch are essentially equal; the council is reluctantly accepted by Pope John VIII of Rome.

962 Denmark becomes Christian nation with baptism of King Harald Blaatand ("Bluetooth"); Holy Roman Empire formed, with Pope John XII crowning Otto I the Great Holy Roman Emperor; Diploma Ottonianum is co-signed by Pope John XII and Otto, confirming the earlier Donation of Pepin, granting control of Papal States to the Popes, regularizing Papal elections, and clarifying the relationship between Popes and oly Roman Emperors.

988 Baptism of Rus' begins with the conversion of Vladimir of Kiev who is baptized at Chersonesos, the birthplace of the Russian and Ukrainian Orthodox churches; Vladimir marries Anna, sister of Byzantine emperor Basil II.

989 The Pax Dei or Peace of God was decreed at the Synod of Charroux, to publicize and enforce what were argued to be eternal principles of protection for churchmen, church property, and the particular protégés of the Church, the poor, becoming a movement that spread to most of Western Europe over the next century, surviving in some form until at least the thirteenth century.

1012 Martyrdom of Alphege, Archbishop of Canterbury; Caliph Al-Hakim bi-Amr Allah issues oppressive decrees against Jews and Christians including the destruction of all Christian and Jewish houses of worship.

1013 Jews expelled from caliphate of Córdoba.

1014 Filioque used for first time in Rome by Pope Benedict VIII at coronation of Henry II, Holy Roman Emperor.

Notes

↑In Moravia, as in Bulgaria, the Greek mission clashed with German missionaries at work in the same area. Traces of the Slavonic mission lingered on in Moravia for two centuries more, but were eventually eradicated; and Christianity in its western form, with Latin culture and the Latin language (and the filioque), became universal. The attempt to found a Slavonic national Church in Moravia came to nothing. After its collapse in Moravia, the work of the Slavic apostles was saved for the Slavs and Europe by Bulgaria when its ruler Boris, in his endeavor to establish a national church, protected and encouraged the Slavic missionaries who sought refuge in his land. Thus, the Cyrillo-Methodian tradition was preserved and further cultivated in Ochrid and Preslav, two great and dissimilar centers which created a rich literature and culture Byzantine in inspiration, yet Slavic in language and ideology. Therefore other countries, where the brothers had not themselves preached, benefited from their work, most notably Bulgaria, Serbia, and Russia.

↑Their palace was in Ostrov Tumski, where the royal couple worshipped in a chapel before Christianity became the official religion. It is the foundations of this chapel, marking the beginning of Christian life in Poland, which archaeologists think that they have now uncovered. Its pre-Romanesque structure shows the Orthodox architectural style of Western Europe before the schism. We should recall that in southern Poland, along the Moravian border which had been ruled by St Rostislav, Slav Orthodox missionaries had begun their task of spiritual enlightenment well before Mieszko’s marriage to Dobrawa. This discovery will surely lead the spiritually sensitive in Poland to realise that the origins of Poland's Christian faith are in Orthodoxy, and not in late eleventh-century Roman Catholicism. This was imported from Germany, and only developed to any great extent in Poland in the twelfth century. (Orthodox England. Orthodox Europe: Poland uncovers its original Orthodoxy.)